Informal use of "Ground Zero"
The use of the term has been expanded and exaggerated in colloquial usage beyond nuclear strikes to cover the centre of any episode of widespread destruction. In particular, the term was widely used (coined by the news media) to describe the former site of the World Trade Center, which was destroyed in the September 11, 2001 terrorist attacks. Rescue workers at the site of the collapse did not use this term as it was considered insensitive, disrepectful, even offensive, to those that died. The phrase "The Pile", as in the pile of rubble that was left after the buildings collapsed, was the term used by the rescue workers themselves. See World Trade Center site for reconstruction news.

To put this usage into perspective, it should be noted that the total energy of the World Trade Center attack was approximately 0.2 kilotons, mostly consisting of the gravitational potential energy of the towers themselves.
If only the kinetic energy and chemical energy of the planes and their fuel is counted, the energy of the attack itself was only 0.02 kT.

This is a small fraction of the energy released by even a small nuclear weapon, to such an extent that the World Trade Center usage of the term can almost be regarded as a euphemism for the real thing.

For comparison, using the upper estimate for the World Trade Center attack energy:

The relatively small 20 kT Nagasaki bomb released approximately 100 World Trade Centers disasters' worth of energy.

A single 300 kT MIRV warhead would release 1500 World Trade Centers disasters' worth of energy.

A single 10 Mt thermonuclear warhead would release 50,000 World Trade Center disasters' worth of energy.

The term is also apparently used by members of the U.S. armed forces to describe the open space at the center of The Pentagon, in a blackly humorous reference to the likelihood of its being a nuclear weapons target in any nuclear war.